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For the first time this season it felt Seattle’s usual. On and off the field.

“It felt like a really normal Seahawks night,” Carroll said.

The defense dominated San Francisco and Marshawn Lynch romped for 122 yards — his most since January’s NFC title game — with a touchdown in a 20-3 steamrolling of the 49ers at a boo-filled Levi’s Stadium.

It could have been far more lopsided.

“That was the way it was supposed to be,” Carroll said. “Yeah, these guys know how to have fun. They’ve done enough winning; they know how to enjoy that.

“It’s really good to feel that again.”

It took Lynch vomiting into a garbage can after rushing nine times for 38 yards and his 1-yard score on the game’s first drive — and 27 total carries, his most in 29 games since a playoff win over New Orleans in January 2014.

It took Michael Bennett’s career-best 31/2 sacks — with a new dance, biceps-kissing and taunts to further enrage the ticked-off natives.

“I was showing off my muscles to my wife,” Bennett said, adding that he changed his sack dance to keep the NFL happy after mandates to stop “sexually suggestive” dances such as his usual hip shimmy.

It took as dominant a first half as the Seahawks have had since … well, the last time they’d played here.

Finally, the Seahawks (3-4) finished a game.

Then again, how could they not against these malfunctioning 49ers?

Bennett’s fellow end, Cliff Avril, continued his outstanding season with 1½ sacks for a defense that smashed Colin Kaepernick and the 49ers offense into ineptitude. San Francisco gained just 142 total yards and punted nine times.

This was the 19th consecutive game that the Seahawks had a lead during the fourth quarter. They held it to win for just the third time in the last nine games.

The Seahawks’ six sacks were a season high, as Seattle won for the fourth consecutive time over San Francisco. The combined scores of the last three wins over the 49ers: 56-13.

“The quarterback held the ball today,” Bennett said. “So it just gave me some time to get there.”

The 49ers (2-5) played even more meekly than they did last season here while rolling over in a 19-3 loss to Seattle. That one was so bad that the 49ers chief executive, Jed York, tweeted an apology to the team’s fans.

He may need to hire a plane to pull an “I’m sorry” banner over the Bay Area following this one. San Francisco’s total yardage was its least since November 2006.

Russell Wilson was a senior in high school in Richmond, Virginia, then.

Wilson completed 18 of 24 passes for 235 yards, one touchdown, two interceptions and five sacks. He was exquisite for most of the first half, having at one point in the second quarter a quarterback rating of 155.8.

His best throw was the prettiest offensive play of the season so far, an arcing pass with rare, good protection. It found rookie Tyler Lockett in stride just past a Niners defender inside the goal line for a 43-yard touchdown late in the second quarter. That made it 17-0.

It should have been a lot more than that.

Wilson threw an interception to end the first half, trying to fit in a pass to Baldwin at the back of the end zone. He threw another one, forcing a deep ball into double coverage to Jermaine Kearse at the San Francisco 12.

Wilson narrowly avoided a third interception when he threw behind Jimmy Graham (two catches, 31 yards) at midfield with four minutes left.

So it could have — should have — been at least 34-3, if not for Wilson’s first two-interception game since last Nov. 9 against the New York Giants.

The first half was as complete a domination as the Seahawks have had since … well, when they were here last Thanksgiving. That 19-3 win ended with Wilson and Richard Sherman drawing San Francisco’s ire for gnawing on turkey at midfield immediately afterward.

The Seahawks sacked Kaepernick four times in this first half, tying the most they’d had in a game before Thursday. San Francisco had 17 net yards passing on 17 drop backs to throw.

One of those ended with Kaepernick overthrowing Anquan Boldin by five yards into the 49ers’ bench, beaning a team trainer who then needed medical attention. Another way-errant Kaepernick throw narrowly missed a startled Niners cheerleader.

The Seahawks began the evening fixing, at least temporarily, one of their biggest problems on offense — though it was a struggle like the rest of this season so far.

Lynch’s twisting dive over the goal line from a yard out, for his second touchdown of the season, ended a 12-play, 61-yard drive to begin the game. Six of those plays came inside the San Francisco 4-yard line.

It was the fifth touchdown in 15 red-zone trips this season for Seattle, and just its second in the last 10 such drives. Seattle was last in the NFL entering Thursday with a meager 28 percent touchdown rate in the red zone.

So do the Seahawks have their punishing defense and running-game swagger back after one, steamrolling night in the South Bay, to deploy again in the Nov. 1 game at Dallas?

“We’re on the verge,” safety and team leader Kam Chancellor said. “We’re in the right direction.”